Process of mordanting wool.



PHILLIPS ROGERS, OF WOLLASTON, UASSAOHUSE'WIS.

PROCESS OF MORDANTING WOOL.

Specification of Letters Patent.

Eatented Feb. 4, 1908.

Application filed May 24.1906- Serial No. 318.462.

To all whom it may concern:

Be it known that I, PHILLIPS Roe-Ens, of l/Vollaston, in the county of Norfolk and State of Massachusetts, have invented certain new and useful Improvements in Processes of Mordanting ool, of which the following is a specification.

This invention relates to the process in the dyeing of wool known as mordanting, in which the woolen fiber is first acted upon by a metallic salt, which combines chemically with certain of the coloring compounds used in dyeing to form a lake; causing the fiber to take deeper and stronger colors, which are insoluble, and therefore more permanent than the colors given to the fiber when the mordant is not used.

One of the most common methods used for mordanting wool is to boil the fiber with a solution of a metallic salt, such as bichromate of potash or soda, with the addition of dilute acid, or an acid salt. The acid or acid salt acts upon the bichromate salt to liberate the chromic acid, which is absorbed by the fiber, and, when the latter is subjected to the color ing matter, combines with the same and fixes it upon the fiber in a form which is insoluble, and comparatively inert to the action of light, thereby producing what is known as a fast color. When acids or acid salts are used to take up the sodium or potassium from the bichromate, the re-action is rapid, with the result that the wool is not evenly acted upon by the mord ant, and, therefore, when placed in the dye bath takes the color in an uneven manner, so that although parts of the fiber may be perfectly dyed, and receive a strong and uniform color, other parts will be given a less pure color.

It is the object of the present invention to perform the mordanting process by the use of a mordant which will liberate the chromic acid gradually and comparatively slowly, so that all of the fiber may be uniformly acted upon by the acid, and a uniform and even color will be obtained from the later action of the dye.

A further object of the invention is to cheapen the process of mordanting, while getting results not only as good as, but even better than those obtained by present more expensive methods.

Accordingly the process which constitutes the present invention consists in treating the Wool to be dyed with bichromate of ammonia,

which, when heated, will break down and libcrate the chromic acid.

In carrying out the invention, I provide a bath made of a solution of salts, which will re-act with each other to form bichromate of ammonia, these being an alkali bichromate, such as that of either potassium or sodium, and an ammonium salt. Any suitable salt of ammonia may be used, but those preferred are the ones which are the most common in commerce and the least expensive, such as the sulfate, chlorid or nitrate, but it is to be understood that instead of these, any salt may be used whose negative element or radical has a stronger a'llinity for potassium or sodium than the bichromate radical. The proportions of the agents in the bath are such as to cause the ammonium salt to act upon the bichromate salt with the formation of a bichromate of ammonia and a salt of potassium or sodium, such as sulfate, chlorid, nitrate, etc. The fiber or fabric to be dyed is boiled in this bath for a period varying from one to one and a half hours, during which the ammonium bichromate is first produced, and is then gradually broken up into chromic acid and ammonia, the chromic acid being absorbed by and deposited on the fiber. The goods are then taken out and washed. \Vhereupon they are ready for dyeing. The re-actions take place approximately according to the formulas as follows:

K O O (N 1 1M50 (NI'L)2C12O7 K 80 After further heating, the biehromate of ammonia is decomposed as follows:

(N HQ Or O, NH, ZOrO H O.

The exact quantities of the ingredients employed in the process are subject to variation according to the depth of mordanting required, but I have found that for ordinary purposes, the best results are obtained when of the alkali bichromate on one hundred pounds of wool is nineteen ounces, while twenty-seven ounces of the nitrate are re quired to do the same work.

The wool may be put into the bath either before or after the latter is brought to the boiling point, it being essential only that it hour and an hour and a half.

should be subjected to the action of the reagents at the temperature of boiling for the period before named, that is, between one It is easier, however, and requires less attention to immerse the wool before the compound begins to boil, and accordingly, the wool and the reagents are put in together into the bath and the latter is then brought to the boiling point.

This process differs from the methods known, in that a neutral salt, instead of an acid or an acid salt, is used to re-act upon the bichromate, whereby the mordant is deposited upon the fiber evenly and slowly, insuring better results in the after dyeing as regards permanence of the dye, and uniformity of color, than are attained by present methods.

By the use of my method, a great economy over prior methods is obtained, on account of the large supply and low cost of the am monium salts available. The processes at the present time most generally in use are performed by the action up on the bichromate salt of either sulfuric acid, oxalic acid, cream of tartar, one-half refined tartar, or lactic acid. Of these the most satisfactory results are obtained when cream of tartar is used,

but the cost of using this product is excessive, and the other acids are used according to the taste and the wealth of the dyer. Generally the results obtained, vary from the best possible, in proportion to the cost of the agents used, but as cream of tartar is so high in price as to be excluded from use on any considerable scale, the best possible results are seldom obtained in actual practice. The ammonium salts, however, are entirely neutral, and therefore are much less active, whereby they avoid the defects of the acids, and equal or eXcel in results the cream of tartar, but, being very plentiful, they are cheap and can therefore be used Where cream of tartar is barred.

The hereinbefore described mordant bath is suitable for acting upon wool or any fabric made rincipally of wool, and is used to prepare the fiber for any of the dyes which require chrome mordanting to form the insoluble lake, that is, any of the dyes which are known as mordant colors, these being the alizarin dyes, and such vegetable dyes as logwood.

I claim 1. The process of mordanting wool which consists in forming ammonium bichromate by the reaction between an alkali bichromate and an ammonium salt, and subsequently decomposing the ammonium bichromate in the presence of the wool.

2. The process of mordanting wool which consists in boiling the wool to be dyed in a bath containing an alkali bichromate and an ammonium salt, With the formation and subsequently decomposition of ammonium bichromate.

3. The process of mordanting wool which consists in forming ammonium bichromate in a bath, in the presence of the wool, from an alkali bichromate and an ammonium salt, by boiling; and decomposing the ammonium bichromate, also in the presence of the wool, by continued boiling.

4. The process of mordanting wool by subjecting the same to the action of a solutiqn of alkali bichromate, and an ammonium sa t.

5. The process of mordanting wool by placing the wool in a bath composed of a solution of an alkali bichromate and a salt of ammonia, and heating the bath.

6. The process or method of mordanting wool which consists in decomposing ammo nium bichromate in the presence of the wool by the application of heat.

In testimony whereof I have afiiXed my signature, in presence of two Witnesses.

A. C. RATIGAN, ARTHUR H. BROWN. 

